How do polar covalent bonds form between atoms?

Polar covalent bonds form through unequal sharing of electrons between two atoms with different electronegativities. Electronegativity is a measure of an atom's ability to attract and hold onto electrons. When two atoms form a covalent bond, they share electrons to achieve a more stable electron configuration. However, if one atom is significantly more electronegative than the other, it will attract the shared electrons more strongly, resulting in an uneven distribution of electron density.

This unequal sharing creates a dipole in the bond, with one end being slightly negative (the more electronegative atom) and the other end being slightly positive (the less electronegative atom). It is this characteristic of polar covalent bonds that leads to unique properties in molecules, such as water, which is critical for biological functions.

Ionic interactions involve the complete transfer of electrons from one atom to another, creating charged ions rather than sharing, and hydrogen bonding is a specific type of attraction that occurs between a hydrogen atom bonded to a highly electronegative atom (like oxygen or nitrogen) and another electronegative atom. These processes do not describe the formation of polar covalent bonds.